An in-vehicle ECU performs controls including ESC (Electronic Stability Control). Such an in-vehicle ECU is provided with a microcomputer but in the event that an abnormality occurs in the microcomputer, the abnormality is required to be monitored. In an example exemplified in PLT 1, a watchdog signal or a monitoring signal in for example in serial communication is used for the monitoring of an abnormality.
These monitoring signals are monitored by a power IC or the like. If a normal state cannot be confirmed through monitoring over a given period, a reset signal is outputted in such an in-vehicle ECU to restart the microcomputer.
Patent Literature 1 JP-A-H11-065893
However, where the microcomputer of an in-vehicle ECU has a BIST (Built In Self Test) function, user programs are not started during a BIST period that follows power-on. Therefore, resultantly, a normal-state signal is not outputted. With this configuration, if this BIST time is longer the time of abnormality monitoring performed by the power IC, a reset signal is outputted before BIST is completed and thus the microcomputer is reset by the output. For this reason, the microcomputer is not able to perform a normal startup operation.